High T sub C superconductors - Composite wire and coil fabrication.

Commercially useful, bulk superconductors typically require stabilization using a normal metal clading for reasons of electrical, thermal, and mechanical protection and, in general, need to be drawn into fine fibers and wound into a magnet configuration. The recent discovery of high-T sub c superconductor materials such as Ba sub 2 YCu sub 3 O sub 7 stimulated worldwide interest in the subject, however, with much concern about fabricability of such brittle ceramic materials into desirable fine wire geometry. In this paper, we report preliminary success in the fabrication of fine-wire composite superconductors consisting of a high conductivity normal metal shell such as Ag or Cu/Ni/Au and a superconducting core of Ba sub 2 YCu sub 3 O sub 7 oxide. The wire is wound into a coil, and then heat treated to produce the desired chemistry in a dense structure. The resistivity of the composite wire is measured to be zero at ~ 90K (in zero field) with a critical current density of ~ 175 A/cm sup 2.